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.Dd May 16, 2023
.Dt PASSWD 5
.Os
.Sh NAME
.Nm passwd ,
.Nm master.passwd ,
.Nm pwd.db ,
.Nm spwd.db
.Nd format of the password file
.Sh DESCRIPTION
The
.Nm
files are the local source of password information.
They can be used in conjunction with the Hesiod domains
.Sq Li passwd
and
.Sq Li uid ,
and the
NIS
maps
.Sq Li passwd.byname ,
.Sq Li passwd.byuid ,
.Sq Li master.passwd.byname ,
and
.Sq Li master.passwd.byuid ,
as controlled by
.Xr nsswitch.conf 5 .
.Pp
For consistency, none of these files should ever be modified
manually.
.Pp
The
.Nm master.passwd
file is readable only by root, and consists of newline separated
records, one per user, containing ten colon
.Pq Ql \&:
separated
fields.
These fields are as follows:
.Bl -tag -width ".Ar password" -offset indent
.It Ar name
User's login name.
.It Ar password
User's
.Em encrypted
password.
.It Ar uid
User's id.
.It Ar gid
User's login group id.
.It Ar class
User's login class.
.It Ar change
Password change time.
.It Ar expire
Account expiration time.
.It Ar gecos
General information about the user.
.It Ar home_dir
User's home directory.
.It Ar shell
User's login shell.
.El
.Pp
The
.Nm
file is generated from the
.Nm master.passwd
file by
.Xr pwd_mkdb 8 ,
has the
.Ar class ,
.Ar change ,
and
.Ar expire
fields removed, and the
.Ar password
field replaced by a
.Ql *
character.
.Pp
The
.Ar name
field is the login used to access the computer account, and the
.Ar uid
field is the number associated with it.
They should both be unique
across the system (and often across a group of systems) since they
control file access.
.Pp
While it is possible to have multiple entries with identical login names
and/or identical user id's, it is usually a mistake to do so.
Routines
that manipulate these files will often return only one of the multiple
entries, and that one by random selection.
.Pp
The login name must not begin with a hyphen
.Pq Ql \&- ,
and cannot contain 8-bit characters, tabs or spaces, or any of these
symbols:
.Ql \&,:+&#%^\&(\&)!@~*?<>=|\e\\&/"\&; .
The dollar symbol
.Pq Ql \&$
is allowed only as the last character for use with Samba.
No field may contain a
colon
.Pq Ql \&:
as this has been used historically to separate the fields
in the user database.
.Pp
Case is significant.
Login names
.Ql Lrrr
and
.Ql lrrr
represent different users.
Be aware of this when interoperating with systems that do not have
case-sensitive login names.
.Pp
In the
.Nm master.passwd
file,
the
.Ar password
field is the
.Em encrypted
form of the password, see
.Xr crypt 3 .
If the
.Ar password
field is empty, no password will be required to gain access to the
machine.
This is almost invariably a mistake, so authentication components
such as PAM can forcibly disallow remote access to passwordless accounts.
Because this file contains the encrypted user passwords, it should
not be readable by anyone without appropriate privileges.
.Pp
A password of
.Ql *
indicates that
password authentication is disabled for that account
(logins through other forms of
authentication, e.g., using
.Xr ssh 1
keys, will still work).
The field only contains encrypted passwords, and
.Ql *
can never be the result of encrypting a password.
.Pp
An encrypted password prefixed by
.Ql *LOCKED*
means that the account is temporarily locked out
and no one can log into it using any authentication.
For a convenient command-line interface to account locking, see
.Xr pw 8 .
.Pp
The
.Ar group
field is the group that the user will be placed in upon login.
Since this system supports multiple groups (see
.Xr groups 1 )
this field currently has little special meaning.
.Pp
The
.Ar class
field is a key for a user's login class.
Login classes
are defined in
.Xr login.conf 5 ,
which is a
.Xr termcap 5
style database of user attributes, accounting, resource,
and environment settings.
.Pp
The
.Ar change
field is the number of seconds from the epoch,
.Dv UTC ,
until the
password for the account must be changed.
This field may be left empty to turn off the password aging feature;
a value of zero is equivalent to leaving the field empty.
.Pp
The
.Ar expire
field is the number of seconds from the epoch,
.Dv UTC ,
until the
account expires.
This field may be left empty to turn off the account aging feature;
a value of zero is equivalent to leaving the field empty.
.Pp
The
.Ar gecos
field normally contains comma
.Pq Ql \&,
separated subfields as follows:
.Pp
.Bl -tag -width ".Ar office" -offset indent -compact
.It Ar name
user's full name
.It Ar office
user's office number
.It Ar wphone
user's work phone number
.It Ar hphone
user's home phone number
.El
.Pp
The full
.Ar name
may contain an ampersand
.Pq Ql &
which will be replaced by
the capitalized login
.Ar name
when the
.Ar gecos
field is displayed or used
by various programs such as
.Xr finger 1 ,
.Xr sendmail 8 ,
etc.
.Pp
The
.Ar office
and phone number subfields are used by the
.Xr finger 1
program, and possibly other applications.
.Pp
The user's home directory,
.Ar home_dir ,
is the full
.Ux
path name where the user
will be placed on login.
.Pp
The
.Ar shell
field is the command interpreter the user prefers.
If there is nothing in the
.Ar shell
field, the Bourne shell
.Pq Pa /bin/sh
is assumed.
The conventional way to disable logging into an account once and for all,
as it is done for system accounts,
is to set its
.Ar shell
to
.Pa /sbin/nologin
.Pq see Xr nologin 8 .
.Sh HESIOD SUPPORT
If
.Sq Li dns
is specified for the
.Sq Li passwd
database in
.Xr nsswitch.conf 5 ,
then
.Nm
lookups occur from the
.Sq Li passwd
Hesiod domain.
.Sh NIS SUPPORT
If
.Sq Li nis
is specified for the
.Sq Li passwd
database in
.Xr nsswitch.conf 5 ,
then
.Nm
lookups occur from the
.Sq Li passwd.byname ,
.Sq Li passwd.byuid ,
.Sq Li master.passwd.byname ,
and
.Sq Li master.passwd.byuid
NIS
maps.
.Sh COMPAT SUPPORT
If
.Sq Li compat
is specified for the
.Sq Li passwd
database, and either
.Sq Li dns
or
.Sq Li nis
is specified for the
.Sq Li passwd_compat
database in
.Xr nsswitch.conf 5 ,
then the
.Nm
file also supports standard
.Sq Li + Ns / Ns Li -
exclusions and inclusions, based on user names and netgroups.
.Pp
Lines beginning with a
.Ql -
(minus sign) are entries marked as being excluded
from any following inclusions, which are marked with a
.Ql +
(plus sign).
.Pp
If the second character of the line is a
.Ql @
(at sign), the operation
involves the user fields of all entries in the netgroup specified by the
remaining characters of the
.Ar name
field.
Otherwise, the remainder of the
.Ar name
field is assumed to be a specific user name.
.Pp
The
.Ql +
token may also be alone in the
.Ar name
field, which causes all users from either the Hesiod domain
.Nm
(with
.Sq Li passwd_compat: dns )
or
.Sq Li passwd.byname
and
.Sq Li passwd.byuid
NIS
maps (with
.Sq Li passwd_compat: nis )
to be included.
.Pp
If the entry contains non-empty
.Ar uid
or
.Ar gid
fields, the specified numbers will override the information retrieved
from the Hesiod domain or the
NIS
maps.
Likewise, if the
.Ar gecos ,
.Ar dir
or
.Ar shell
entries contain text, it will override the information included via
Hesiod or
NIS .
On some systems, the
.Ar passwd
field may also be overridden.
.Sh FILES
.Bl -tag -width ".Pa /etc/master.passwd" -compact
.It Pa /etc/passwd
ASCII
password file, with passwords removed
.It Pa /etc/pwd.db
.Xr db 3 Ns -format
password database, with passwords removed
.It Pa /etc/master.passwd
ASCII
password file, with passwords intact
.It Pa /etc/spwd.db
.Xr db 3 Ns -format
password database, with passwords intact
.El
.Sh COMPATIBILITY
The password file format has changed since
.Bx 4.3 .
The following awk script can be used to convert your old-style password
file into a new style password file.
The additional fields
.Ar class ,
.Ar change
and
.Ar expire
are added, but are turned off by default
.Pq setting these fields to zero is equivalent to leaving them blank .
Class is currently not implemented, but change and expire are; to set them,
use the current day in seconds from the epoch + whatever number of seconds
of offset you want.
.Bd -literal -offset indent
BEGIN { FS = ":"}
{ print $1 ":" $2 ":" $3 ":" $4 "::0:0:" $5 ":" $6 ":" $7 }
.Ed
.Sh SEE ALSO
.Xr chpass 1 ,
.Xr login 1 ,
.Xr passwd 1 ,
.Xr crypt 3 ,
.Xr getpwent 3 ,
.Xr login.conf 5 ,
.Xr netgroup 5 ,
.Xr nsswitch.conf 5 ,
.Xr adduser 8 ,
.Xr nologin 8 ,
.Xr pw 8 ,
.Xr pwd_mkdb 8 ,
.Xr vipw 8 ,
.Xr yp 8
.Pp
.%T "Managing NFS and NIS"
(O'Reilly & Associates)
.Sh HISTORY
A
.Nm
file format first appeared in
.At v1 .
.Pp
The
NIS
.Nm
file format first appeared in SunOS.
.Pp
The Hesiod support first appeared in
.Fx 4.1 .
It was imported from the
.Nx
Project, where it first appeared in
.Nx 1.4 .
.Sh BUGS
User information should (and eventually will) be stored elsewhere.
.Pp
Placing
.Sq Li compat
exclusions in the file after any inclusions will have
unexpected results.
